The Barcelona midfielder has been sidelined several times by muscle problems in recent months and the 33-year-old was absent for the La Liga leaders' 3-1 victory at home to Rayo Vallecano on Sunday before joining up with the world and European champions in Madrid.
The Spanish football federation said on their website Xavi had undergone tests on Tuesday and would work alone in the next couple of days before rejoining his team mates.
Coach Vicente del Bosque is unlikely to risk him against Finland in Gijon in the hope he is fit for Tuesday's crunch clash against France in Paris.
"We all know Xavi and he is a player who gives us a lot of control in the middle," winger Jesus Navas said.
"But we have players who can take his place in that position and we hope he is back with us again soon," he added.
Spain and France, who drew 1-1 in Madrid in October, top the five-nation group on seven points from three matches.
Georgia, who play France in Paris on Friday, are third on four points.